A Novel Scheme for Flexible NURBS-based C2 PH Spline Curve Contour Following Task using Neural Network

Mahdi Karimi,Javad Jahanpour,Shahab Ilbeigi 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

In this paper, a novel scheme for approximation of complicated CNC tool paths, designed by non-uniform rational B-spline (NURBS)curves, is proposed. The idea of this approximation is based on introducing flexible NURBS-based C2 PH Spline Curves. Using thespecifications of nodal points on a NURBS curve and introducing the coefficients for the velocity and acceleration vectors on thesepoints, as well as defining flexible connection nodes, a new method is presented to design a tool path via C2 PH spline curves. Valuesof the velocity/acceleration vector coefficients corresponding to the flexible connection nodes on the original NURBS curve arecomputed by genetic algorithm and Neural Network. To this end, the normal distance between the tool path and its correspondingoriginal NURBS curve is considered as the objective function. Using combination of the time-dependent feedrate and constantfeedrate interpolations, the position commands of the designed curve are generated. Several contour following tasks wereimplemented with pseudo-derivative feedback feed forward (PDFF) controller. Experimental and simulation results confirm that thedevised interpolator is not only feasible for machining the complicated tool path represented in the improved NURBS-based C2 PHspline form but also yields satisfactory contouring performance under variable feedrate.

Relationships for prediction of backstay effect in tall buildings with core-wall system

Karimi, Mahdi,Kheyroddin, Ali,Shariatmadar, Hashem Techno-Press 2020 Advances in computational design Vol.5 No.1

One of the prevailing structural systems in high-rise buildings is the core-wall system. On the other hand, the existence of one or more underground stories causes the perimeter below-grade walls with the diaphragm of grade level to constitute of a very stiff box. In this case or a similar situation, during the lateral response of a tall building, underground perimeter walls and diaphragms that provide an increased lateral resistance relative to the core wall may introduce a prying action in the core that is called backstay effect. In this case, a rather great force is generated at the diaphragm of the grade-level, acting in a reverse direction to the lateral force on the core-wall system, and thus typically causes a reverse internal shear. In this research, in addition to review of the results of the preceding studies, an improved relationship is proposed for prediction of backstay force. The new proposed relationship takes into account the effect of foundation flexibility and is presented in a non-dimensional form. Furthermore, a specific range of the backstay force to lateral load ratio has been determined. And finally, it is shown that although all suggested formulas are valid in the elastic domain, yet with some changes in the initial considerations, they can be applied to some certain non-linear problems as well.

Iran’s Foreign Policy toward Tajikistan: Exploring the Effective Factors

Karimi Mahdi,Osuli Odlu Qasem 한양대학교 아태지역연구센터 2023 Journal of Eurasian Studies Vol.14 No.2

After the independence of the Central Asian (CA) republics, Iran has tried to develop its relations with these sates, especially with Tajikistan. The development of bilateral relations between Iran and Tajikistan has been very important for both sides. But after nearly 30 years of political relations between Iran and Tajikistan, bilateral relations have not developed much and have faced numerous limitations. By adopting Rosenau’s theory, the current study aims at investigating Iran’s foreign policy (FP) toward Tajikistan and the factors influencing the bilateral relations between the two countries. The present paper argues that societal, governmental, idiosyncratic, and role variables, respectively, have hindered the development of bilateral relations between Iran and Tajikistan. Finally, systemic variables have had the least influence on Iran’s relations with Tajikistan, and the results show that the U.S. and its sanctions have had insignificant effect on Iran–Tajikistan bilateral relations, and in terms of the systemic variables, Iran has faced more opposition from China than any other country in the development of relations with Tajikistan.

Increase in the Th1-Cell-Based Immune Response in Healthy Workers Exposed to Low-Dose Radiation - Immune System Status of Radiology Staff

Karimi, Gholamreza,Balali-Mood, Mahdi,Alamdaran, Seyed-Ali,Badie-Bostan, Hassan,Mohammadi, Elaheh,Ghorani-Azam, Adel,Sadeghi, Mahmood,Riahi-Zanjani, Bamdad KOREAN PHARMACOPUNCTURE INSTITUTE 2017 Journal of pharmacopuncture Vol.20 No.2

Objectives: Radiation is one of the most important sources of free radical (such as reactive oxygen species) production, which plays an essential role in the etiology of over hundred diseases. The aim of the study was to investigate some immune parameters and hematological indices in healthy workers of the Radiology Department, University Hospital of Mashhad, Iran. Methods: The study was performed on 50 healthy workers: 30 radiology staff as the case group and 20 laboratory workers as the control group. The radiation dose received by the radiology staff participating in the study was less than the annual maximum permissible level, 50 millisievert. Hematological parameters, lymphocyte proliferation and cytokine production were studied in both groups. Results: Among healthy radiology workers, the hematological indices did not differ statistically; however, their proliferation indices and $IFN-{\gamma}$ levels showed significant increases in parallel with decreases in the IL-4 levels as compared to controls. The immune system of workers exposed to low-dose ionizing radiation was found to be shifted from a Type 2 to a Type 1 response to promote cellular immunity. Conclusion: Based on our data, exposure to low-dose ionizing radiation may decrease the prevalence, frequency, and recurrence of various cancers and infectious diseases because of an increase in Th1-cell-based response, thus leading to more protection of the human body against tumor cells and foreign agents and possibly increased longevity. However, due to high rate of fluoroscopy use for interventional radiology, we suggest continuing research projects on radiation protection and hazards to prevent irreversible damage. As a recommendation, in future studies, radiology staff with a weakened immunity due to high radiation exposure should be considered as good choices to be treated using acupuncture techniques because acupuncture has been demonstrated to enhance the function and the number of immune cells.

Numerical and experimental investigation of vortex breaker effectiveness on the improvement in launch vehicle ballistic parameters

Mahdi N. Mahyari,Hasan Karimi,Hasan Naseh,Mehran Mirshams 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.10

The focus of the present study is to investigate the effectiveness of installing vortex breakers at the outlet of launch vehicle tanks on postponing vortex formation and decreasing the critical height of propellants while discharging. Analytical results in the absence of a vortex breaker show that the effects of the Weber and Reynolds numbers in the flow field can be ignored for values greater than 720 and 1.1 × 105, respectively; and critical height can be considered as a function of Froude number under aforementioned conditions. The analytical criteria are verified by two-dimensional, axis symmetrical, transient and two-phase numerical model. Eventually, some experiments are conducted to examine the effectiveness of the applied vortex breakers in reduction of the critical height of propellant. Experimental results show that a 30% decrease can be achieved in critical height by using a particular type of vortex breaker. Additionally, the carried out simulations for an existing two-stage launch vehicle indicate a 13% increase in orbital altitude, which in turn proves the considerable improvement in launch vehicle mass/energetic capabilities.

Modeling and Experimental production yield of 64Cu with natCu and natCu-NPs in Tehran Research Reactor

Zahra Karimi,Mahdi Sadeghi,Arsalan Ezati 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1

64Cu is a favorable radionuclide in nuclear medicine applications because of its unique characteristicssuch as three types of decay (electron capture, band bþ) and 12.7 h half-life. Production of 64Cu byirradiation natCu and natCuNPs in Tehran Research Reactor was investigated. The characteristics of coppernanoparticles were investigated with SEM, TEM and XRD analysis. The cross section of 63Cu(n,g)64Cureaction was done with TALYS-1.8 code. The activity value of 64Cu was calculated with theoreticalapproach and MCNPX-2.6 code. The results were compared with related experimental results whichshowed good adaptations between them.

Contra-diffusion synthesis of ZIF-8 layer on polyvinylidene fluoride ultrafiltration membranes for improved water purification

Atefeh Karimi,Vahid Vatanpour,Alireza Khataee,Mahdie Safarpour 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.73 No.-

Contra-diffusion synthesis method was used to create a uniform layer of zeolitic imidazolate framework-8 (ZIF-8) on the porous polyvinylidenefluoride (PVDF) ultrafiltration membranes. SEM, FTIR, EDX, AFMand water contact angle analyses were used to characterize the prepared membranes. The modifiedmembrane with 5 h contra-diffusion synthesis time showed maximum pure waterflux of 134 L/m2 hnearly twice of that of the bare PVDF membrane (65.8 L/m2 h). The water purification performance of theprepared membranes was evaluated using dye removal efficiency and the ZIF-8 modified membranesexhibited better performance for dye removal due of the negatively charged surface.

Decreased Levels of Spleen Tissue CD4+CD25+Foxp3+ Regulatory T Lymphocytes in Mice Exposed to Berberine

Gholamreza Karimi,Mahmoud Mahmoudi,Mahdi Balali-Mood,Maryam Rahnama,Shahrzad Zamani Taghizadeh Rabe,Nafiseh Tabasi,Bamdad Riahi-Zanjani 사단법인약침학회 2017 Journal of Acupuncture & Meridian Studies Vol.10 No.2

The effects of isoquinoline alkaloid berberine (BER) on spleen tissue CD4þCD25þFoxp3þ regulatory T (Treg) cells were evaluated in BALB/c mice. Here, BER was administered daily by intraperitoneal injection at doses of 5 mg/kg and 10 mg/kg for 14 days. Following the exposure, mice spleen cellularities, IL-10 production by splenocytes, and spleen Treg/CD4þ cell profiles were studied in all the test groups of animals. The results showed that a high dose of BER (10 mg/kg) could decrease both the absolute and relative percentages of spleen Treg cells as well as decrease the production of IL-10 by splenocytes in the treated mice (p < 0.05). BER at 5 mg/kg did not appear to affect any of these parameters. Based on the finding here, it would seem that BER has effective immunostimulatory properties, which contradicts the results from other studies indicating immunosuppressive effects of BER. Depending on the doses of BER used, it might have a broad spectrum from immunosuppressive to stimulatory effects. Further studies, including more doses, are required to better evaluate the effects of this natural product. Mechanistic studies are required, particularly in case of redox state of the immune cells, to elucidate and determine how BER functions to impart the toxicity effects demonstrated here and in other studies.

Increase in the Th1-Cell-Based Immune Response in Healthy Workers Exposed to Low-Dose Radiation - Immune System Status of Radiology Staff

Gholamreza Karimi,Mahdi Balali-Mood,Seyed-Ali Alamdaran,Hassan Badie-Bostan,Elaheh Mohammadi,Adel Ghorani-Azam,Mahmood Sadeghi,Bamdad Riahi-Zanjani 대한약침학회 2017 Journal of pharmacopuncture Vol.20 No.2

Objectives: Radiation is one of the most important sources of free radical (such as reactive oxygen species) production, which plays an essential role in the etiology of over hundred diseases. The aim of the study was to investigate some immune parameters and hematological indices in healthy workers of the Radiology Department, University Hospital of Mashhad, Iran. Methods: The study was performed on 50 healthy workers: 30 radiology staff as the case group and 20 laboratory workers as the control group. The radiation dose received by the radiology staff participating in the study was less than the annual maximum permissible level, 50 millisievert. Hematological parameters, lymphocyte proliferation and cytokine production were studied in both groups. Results: Among healthy radiology workers, the hematological indices did not differ statistically; however, their proliferation indices and IFN-γ levels showed significant increases in parallel with decreases in the IL-4 levels as compared to controls. The immune system of workers exposed to low-dose ionizing radiation was found to be shifted from a Type 2 to a Type 1 response to promote cellular immunity. Conclusion: Based on our data, exposure to low-dose ionizing radiation may decrease the prevalence, frequency, and recurrence of various cancers and infectious diseases because of an increase in Th1-cell-based response, thus leading to more protection of the human body against tumor cells and foreign agents and possibly increased longevity. However, due to high rate of fluoroscopy use for interventional radiology, we suggest continuing research projects on radiation protection and hazards to prevent irreversible damage. As a recommendation, in future studies, radiology staff with a weakened immunity due to high radiation exposure should be considered as good choices to be treated using acupuncture techniques because acupuncture has been demonstrated to enhance the function and the number of immune cells.

Analytical post-heating behavior of concrete-filled steel tubular columns containing tire rubber

Amirhossein Karimi,Mahdi Nematzadeh,Saleh Mohammad-Ebrahimzadeh-Sepasgozar 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.6

This research focused on analyzing the post-fire behavior of high-performance concrete-filled steel tube (CFST) columns, with the concrete containing tire rubber and steel fibers, under axial compressive loading. The finite element (FE) modeling of such heated columns containing recycled aggregate is a branch of this field which has not received the proper attention of researchers. Better understanding the post-fire behavior of these columns by measuring their residual strength and deformation is critical for achieving the minimum repair level required for structures damaged in the fire. Therefore, to develop this model, 19 groups of confined and unconfined specimens with the variables including the volume ratio of steel fibers, tire rubber content, diameter-to-thickness (D/t) ratio of the steel tube, and exposure temperature were considered. The ABAQUS software was employed to model the tested specimens so that the accurate behavior of the FE-modeled specimens could be examined under test conditions. To achieve desirable results for the modeling of the specimens, in addition to the novel procedure described in this research, the modified versions of models presented by previous researchers were also utilized. After the completion of modeling, the load-axial strain and load-lateral strain relationships, ultimate strength, and failure mode of the modeled CFST specimens were evaluated against the test data, through which the satisfactory accuracy of this modeling procedure was established. Afterward, using a parametric study, the effect of factors such as the concrete core strength at different temperatures and the D/t ratio on the behavior of the CFST columns was explored. Finally, the compressive strength values obtained from the FE model were compared with the corresponding values predicted by various codes, the results of which indicated that most codes were conservative in terms of these predictions.